The efficient use of riparian groundwater has been proposed to improve the flow regime of an urban river. In case of a tidal river, it seems that dynamic interactions arise between stream and aquifer. However, its actual condition and mechanism of the water exchange have not been clarified precisely. This research consists of two parts. First part is the numerical simulation on response process of riparian aquifer to a tidal stream. Governing factors on the groundwater behavior and the water exchange process were evaluated by a hydraulic model. Moreover, second part is the field observation on behavior of unconfined groundwater and piezometric head under riverbed in the Horikawa River Basin in Nagoya. The observed data of groundwater are reproduced by the simulation model, and the cyclical repetition of infiltration and exfiltration through the riverbed were verified based on the piezometric head behavior in response to the tidal fluctuation.
